That is, the major axis of the Americas is north–south.

也就是说，美洲主轴线是南北向。

It lacks the severe ecological barriers transecting the major axes of the Americas and Africa.

有横贯美洲和非洲主轴线严重生态障碍。

In contrast, the major axis of Eurasia is east–west.

相比之下，欧亚大陆主轴线是西向。

Its east–west major axis permitted many inventions adopted in one part of Eurasia to spread relatively rapidly to societies at similar latitudes and climates elsewhere in Eurasia.

西向主轴使得欧亚大陆某一地区采用许多发明能够相对较快地传播到欧亚大陆其他地区类似纬度和气候社会。

I think our good friend Aaron Levy, you know, laid this out pretty well in this tweet here where he talks about these three major axes, the things that, you know, are most likely to be replaced.

我认为我们好友亚伦·利维在这条推文中已经很好地阐述了这一点，他谈到了这三个主要方面，即那些最有可能被取代事物。